State Senate Majority Leader Ellen Corbett points to her "I Voted" sticker after finishing her ballot at her polling place at Burbank Elementary School in Hayward, Calif., on election day Tuesday, June 3, 2014. Corbett is challenging fellow Democrat Rep. Eric Swalwell in the 15th Congressional District. (Laura A. Oda/Bay Area News Group)

Rep. Eric Swalwell held his commanding lead in the 15th Congressional race, while it took hours before Republican challenger, Hugh Bussell, emerged as the likely number two over state Senate Majority Leader Ellen Corbett in Tuesday's primary election. .

Swalwell, D-Dublin, drew about 48 percent of the vote while Bussell, of Livermore, led Corbett, D-San Leandro, by 610 votes, or about one percentage point.

"We've worked very hard and the results are very clear," Swalwell said late Tuesday night. "Regardless of who finishes second, I think that's the take-away here -- new energy is what they got in 2012, and the people of this district are not looking backward, they're looking forward."

Swalwell, 33, two years ago was a Dublin councilman and the insurgent David who toppled his own party's veteran Goliath, 20-term incumbent Rep. Pete Stark. Now, if the results hold, the freshman will be challenged in his bid for a second term by Bussell, 55, vice chairman of the Alameda County Republican Central Committee.

Swalwell has the endorsements from major Democratic officials and entities from President Obama to the state party; Corbett was endorsed by most local Democratic clubs and by labor unions. Swalwell held a huge fundraising edge throughout the campaign.

In 2012, after a conservative independent was eliminated in the top-two primary, Swalwell not only peeled Democrats away from Stark but also drew independents and Republicans who would vote for anyone but Stark. .